Due to manufacturing variations, both N-type and P-type Metal Oxide Silicon transistors (i.e., NMOS and PMOS transistors) in different wafers have different driving capabilities or different operational currents. A transistor is called “fast” (“F”) if the transistor has a driving capability higher than that of a normal or an average transistor. In contrast, a transistor is “slow” (“S”) if the transistor has a driving capability lower than that of an average transistor. Commonly, the symbols FF, FS, SF, and SS refer to fast NMOS fast PMOS, fast NMOS slow PMOS, slow NMOS fast PMOS, and slow NMOS slow PMOS transistors, respectively.
Writing data to a Static Random Access Memory (SRAM) in many situations is involved with changing the data already stored in the memory storage node, and is generally based on a pulse width of a word line. At some “difficult” conditions, including, for example, when the transistors are SS and SF and writing is performed at some particular operational voltages, and/or temperatures, changing the data is difficult. For another example, in some approaches, a VDDA power supply drives the PMOS or the pull up side, and a VDD power supply drives the NMOS or the pull down side of the memory cell. When voltage VDDA is greater than voltage VDD, the PMOS side causes difficulty to flip the data to effectively write the data to the memory storage node. Increasing the pulse width of the word line improves the situations, but also reduces the operational frequencies.
Like reference symbols in the various drawings indicate like elements.